Fish reveals his real name is Ambrose when he reunites with a dying Levi in Season 1 Episode 5, Digging Up Bones.
Season 1 Edit
Being homosexual back in their time was much more difficult, so they felt an immediate connection. According to Fish, they fall in love when Levi convinces Fish to get his picture taken. They stare at each other while Fish holds still for the long time it takes to expose the film and have fallen in love by the time it is over. They promised each other to meet up if they were both brought back from hell.